The interior Radon transform arises from a limited data problem in computerized tomography. The corresponding operator R is investigated as a mapping between wightedL 2-spaces. Our result is the explicit construction ...The interior Radon transform arises from a limited data problem in computerized tomography. The corresponding operator R is investigated as a mapping between wightedL 2-spaces. Our result is the explicit construction of a singular value decomposition for R. This immediately leads to an inversion formula by series expansion and range characterizations.展开更多
We study an approach to integer wavelet transform for lossless compression of medical image in medical picture archiving and communication system (PACS). By lifting scheme a reversible integer wavelet transform is gen...We study an approach to integer wavelet transform for lossless compression of medical image in medical picture archiving and communication system (PACS). By lifting scheme a reversible integer wavelet transform is generated, which has the similar features with the corresponding biorthogonal wavelet transform. Experimental results of the method based on integer wavelet transform are given to show better performance and great applicable potentiality in medical image compression.展开更多
Alpine forest soil in the southeastern Qinghai–Xizang Plateau plays a crucial role in regional and global climate and biogeochemical cycles,yet the elevational distribution of soil nitrogen(N)availability and losing ...Alpine forest soil in the southeastern Qinghai–Xizang Plateau plays a crucial role in regional and global climate and biogeochemical cycles,yet the elevational distribution of soil nitrogen(N)availability and losing risk is unresolved.In this study,we characterized soil N composition and key N transformation processes across different elevations in 3 typical mounts of the Qinghai–Xizang Plateau.In contrast to previous suggestions,soil total N and ammonium are found to accumulate in high elevation zones.This accumulation of N at higher altitudes is due to a consistent soil net N mineralization rate coupled with an extremely low net nitrification rate,which is suppressed by low p H and high soil moisture in high elevation zones.Moreover,the elevated rates of biological N fixation along the elevation further contribute to N accumulation in high elevation regions in which the acid-tolerant Bradyrhizobium,plant-associated Herbaspirillum,and Klebsiella are identified as the key diazotrophic microbial taxa responsible for active N fixation.Collectively,our results suggest that total N and NH_(4)^(+)-N accumulation in higher altitude zone is a ubiquitous phenomenon in the southeast Qinghai–Xizang Plateau,with lower nitrification rates and higher biological nitrogen fixation being key processes enabling this occurrence.展开更多
基金Supported by the Foundation of the Ministry of Education of China and the Science Foundation of Wuhan University
文摘The interior Radon transform arises from a limited data problem in computerized tomography. The corresponding operator R is investigated as a mapping between wightedL 2-spaces. Our result is the explicit construction of a singular value decomposition for R. This immediately leads to an inversion formula by series expansion and range characterizations.
文摘We study an approach to integer wavelet transform for lossless compression of medical image in medical picture archiving and communication system (PACS). By lifting scheme a reversible integer wavelet transform is generated, which has the similar features with the corresponding biorthogonal wavelet transform. Experimental results of the method based on integer wavelet transform are given to show better performance and great applicable potentiality in medical image compression.
基金supported by the Second Qinghai-Xizang Plateau Scientific Expedition and Research Program(2019QZKK0306 and 2019QZKK0308)
文摘Alpine forest soil in the southeastern Qinghai–Xizang Plateau plays a crucial role in regional and global climate and biogeochemical cycles,yet the elevational distribution of soil nitrogen(N)availability and losing risk is unresolved.In this study,we characterized soil N composition and key N transformation processes across different elevations in 3 typical mounts of the Qinghai–Xizang Plateau.In contrast to previous suggestions,soil total N and ammonium are found to accumulate in high elevation zones.This accumulation of N at higher altitudes is due to a consistent soil net N mineralization rate coupled with an extremely low net nitrification rate,which is suppressed by low p H and high soil moisture in high elevation zones.Moreover,the elevated rates of biological N fixation along the elevation further contribute to N accumulation in high elevation regions in which the acid-tolerant Bradyrhizobium,plant-associated Herbaspirillum,and Klebsiella are identified as the key diazotrophic microbial taxa responsible for active N fixation.Collectively,our results suggest that total N and NH_(4)^(+)-N accumulation in higher altitude zone is a ubiquitous phenomenon in the southeast Qinghai–Xizang Plateau,with lower nitrification rates and higher biological nitrogen fixation being key processes enabling this occurrence.
